A Nike advertising campaign once urged us to realize "we are all witnesses" to the greatness of LeBron James. Las Vegas bettors, however, are currently witnessing historic disappointment with The King.

Relative to Vegas odds, the 2017-18 Cleveland Cavaliers are the single most underachieving NBA team of the past three decades. This season's putrid 11-33-1 record against the point spread is on pace to rank dead last among all 816 teams since 1990-91, the first season for which data is available within ESPN's betting database.

"There's rarely a better bet in the sporting world than against a highly talented team with big expectations that drastically underperforms," professional bettor and ESPN contributor Erin Rynning said.

Cleveland (27-18) has lost five of six and nine of 12 games overall. In the Eastern Conference standings, the Cavs (six games back of the Celtics) are closer to a lottery-bound ninth seed than the top seed. Yet, the betting public remains undeterred.

"They have not quit betting the Cavaliers, I can tell you that," William Hill director of trading Nick Bogdanovich said, sharing that the house continues to profit on Cavs games. "Anytime they face a supposed inferior team, they always draw money."

And that's when it becomes even costlier. Cleveland is 6-30-1 as a favorite, a .176 win percentage which would be the worst such record in ESPN's data set. Plus, the Cavs are 0-12 as double-digit favorites, the longest such losing streak on record. Nonetheless, the public continues to support the Cavs.

Add a horrific against-the-spread record to the list of the Cavaliers' struggles. AP Photo/Alex Goodlett

"It's just hard for the public to go away when you have a commodity like LeBron, " said Westgate Las Vegas Superbook head NBA oddsmaker Jeff Sherman. "Look at what the public does with Tiger [Woods], even though there's no reason to bet on him."

A $100 bettor would be down $2,530 backing Cleveland this year, but only a small percentage are capitalizing on the poor lines and betting against the Cavs. Thus, oddsmakers have no incentive to adjust, thanks to the historically stubborn squares.

"What we do as bookmakers is we put up a number that the public will most likely lay at times," said Wynn sportsbook executive director John Avello. "If that is not working for us, then we'll make an adjustment. But that's not happening right now."

In his personal power rankings, Sherman considers the Cavs the sixth-best team, down three spots from the preseason. Rynning categorizes them an "average" team with the likes of the Miami Heat and Detroit Pistons, stressing that he will continue to fade them until he sees market correction.

"The perception is that they're the best team in the Eastern Conference with LeBron always going to the Finals," Rynning said, citing LeBron's current run of seven straight NBA Finals appearances. "The reality is they're the oldest team and one of the worst defensive teams."

Cleveland just allowed 148 points to the Oklahoma City Thunder on Saturday, the most ever by a LeBron team. The Cavs rank second-to-last in the NBA in defensive efficiency. Over the past decade, no team has reached the playoffs with that ranking at the season's midpoint.

LeBron intensified that drama over the weekend with cryptic comments about the future of coach Tyronn Lue. Opponents are outscoring Cleveland by 10 points per game in January, which is on pace for the worst month of James' 15-year career.

While the Cavs ponder making a deal before the NBA's Feb. 8 trade deadline, the betting public continues to back a team that has rewarded them only 25 percent this season. What will it take for that to stop?